Oystein
Penultimate Amazing
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Miragememories
Banned
I would argue that the NIST has not been consistent and that they have made serious errors which impact on the credibility of their 7WTC collapse hypothesis.
In their 2008 WTC7 Final Report, the NIST claimed the girder seat at column 79 was only 11 inches, and they estimated a fire-induced 600°C steel temperature would result in the necessary 5.5 inch expansion to create girder walk off.
The complaints came in but the NIST hung tough.
Finally, four years later, in 2012, the NIST issued a critical data correction which revealed a fatal flaw in their hypothesis for collapse initiation.
They..cough, cough…acknowledged a "typo".
The girder was pushed off an 12 inch seat, and not the 11 inch seat their calculations were based on.
In an obvious attempt to 'save' their hypothesis, the NIST also claimed a "transposition error" occurred regarding how much the 'pushing' beams expanded.
Instead of the original 5.5 inches, the NIST now claimed it should have been 6.25 inches.
Big problem.
Based on their own figures, the steel temperature required to attain the necessary expansion of 6.25 inches has to be around 736°C.
But, at that temperature, the NIST has already claimed the steel beams would lose significant strength and be sagging. Therefore, no longer pushing.
The NIST have never explained this fatal-to-their-hypothesis contradiction.
It in no way proves that it can!
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That's what you got wrong. The beams didn't need to expand
They didn't need to, because it's not fatal. It's not even a contradiction.
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What does it show?
It shows that the column detail that NIST based their analysis on was inaccurate. NIST were fully aware of another drawing called out as 9114 in which the column detail of the girder to C79 connection clearly had stiffeners attached. Instead they chose to model that connection identical to that of C81 with the exception of the angle that the girder framed in at.
NIST claimed publicly to have a level of detail in BOTH models that was incredibly accurate, and to have modelled each connection individually.....
However, the reality is that the model for the critical connection at C79 was simply a duplicate of the C81 connection. The two were not the same.
Even worse, the C79 connection in LSDYNA was not even the correct TYPE of connection.
NIST did not model the connection in the manner they later claimed to have, in either of the models.
They made some corrections and admitted using some incorrect figures in their report, but they did not address the consequences of their errors because to have done so would have invalidated their initiating event theory.
ETA interesting to find that the seat width at the C81 connection was 11", which was what NIST claimed the seat width to be at C79.
As for the 5.5 Vs 6.25" "typo" that they claimed led to this, that brings us back to axial Vs lateral travel, and pgimeno has already stated that the ANSYS element did not in fact indicate the travel failure of the C79 girder.
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No, it doesn't. "Frankel 1985" is a reference. It's listed in the REFERENCES section. All the other
Let me repeat the post that you must have missed:
_____________________________
And you surely can support that claim, right?
While you get on it, let me paste you some quotes and the REFERENCES section in NCSTAR 1-9 Chapter 2 p.15.
The quotes:
The structural design drawings (Cantor 1985) specified design forces for connections and suggested a typical detail, but did not show specific connection designs; this was standard practice on the U.S. east coast. The erection drawings (Frankel 1985) indicated that design shear forces for the typical beam and girder connections were to be taken from the American Institute of Steel Construction (AISC) beam design tables for beams without shear studs, using 1.5 times those forces for beams with shear studs. The fabrication shop drawings (Frankel 1985a) were used to confirm information about floor connections, which NIST obtained from the structural and erection drawings and from photographs taken during renovations conducted during 1989 to 1990 on a number of floors. [...]
And the references (p.45):
2.7 REFERENCES
[...]
Cantor 1985. Irwin G. Cantor P.C., Structural Engineers, Structural Drawings, 7 World Trade Center.
Cantor 1988. Irwin G. Cantor P.C., Structural Engineers, Structural Drawings for Salomon Brothers 7
World Trade Center Headquarters.
Frankel 1985. Frankel Steel Limited, Erection Drawings, 7 World Trade Center.
Frankel 1985a. Frankel Steel Limited, Fabrication Shop Drawings, 7 World Trade Center (drawing set was not sealed).
[...]
Cantor 1985. Irwin G. Cantor P.C., Structural Engineers, Structural Drawings, 7 World Trade Center.
Cantor 1988. Irwin G. Cantor P.C., Structural Engineers, Structural Drawings for Salomon Brothers 7
World Trade Center Headquarters.
Frankel 1985. Frankel Steel Limited, Erection Drawings, 7 World Trade Center.
Frankel 1985a. Frankel Steel Limited, Fabrication Shop Drawings, 7 World Trade Center (drawing set was not sealed).
And in page 359-360:
8.11 REFERENCES
[...]
Frankel 1985. Frankel Steel Limited, Erection Drawings, 7 World Trade Center.
Frankel 1985a. Frankel Steel Limited, Fabrication Shop Drawings, 7 World Trade Center (drawing set was not sealed).
[...]
Frankel 1985. Frankel Steel Limited, Erection Drawings, 7 World Trade Center.
Frankel 1985a. Frankel Steel Limited, Fabrication Shop Drawings, 7 World Trade Center (drawing set was not sealed).
Are they talking about the same thing? Let's see the captions of some figures.
Whatever the correct drawing number is, it must contain a hell of a lot of information!
Oh Gerry, Gerry... Why don't you listen when I tell you to drop that strategy?
Seriously, stop with the ad-hom. It backfires on you every time.
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No, it wasn't that element indeed. Walk-off was determined by monitoring the lateral distance between the girder and the seat.
DGM
Skeptic not Atheist
Worth highlighting:
Typicly adding an 's' to the end of drawing would mean more than one. Would you agree Gerry?
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So you agree with Mr Sunder's statement above, that the column connections were modelled correctly in both models?
If so, where do NIST account for the stiffener plates shown in drawing 9114?
Also, what pushed the girder in ANSYS to the point where it fitted NISTs criteria to be deemed to have failed?
LSSBB
Devilish Dictionarian
Which girder? You mentioned the C79 girder before. Several were attached to C79 and more than one connection failed.
DGM
Skeptic not Atheist
Why were they needed for the model?
You keep pushing this as important but never prove why, get to work. Do you just want people to trust your belief? You can't seem to convince anyone in the engineering world.
Well, can you show me where in the analytical model should these plates have been added? Once the CoG of the girder was off the seat, the girder would be doomed.
You keep asking the wrong question. The criteria to be deemed to have failed was not the movement of the girder alone. It was the relative distance between the girder and the seat.
A2001 was pushed west by the beams east of it, possibly with leveraging which would have made the distance at the end greater than the distance the beams expanded. The seat was pushed east by the girder west of the column.
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LSSBB
Devilish Dictionarian
Tolerance stack ups doom the whole argument as it is. He is still taking elements in isolation. Pristine building...
Absolutely yes.
Here is an example of NIST admitting that the E12/13 drawing was incorrectly referenced and referring to "cantor 1985". Note that they are stating that the drawing <-SINGULAR, covers 35 floors.
Also worth noting that they use "drawingS"<- PLURAL in the "footnote 2" admission of error, and that drawing 1985 includes these floors (29 - >31)
By 2012 NIST are all over the place, drowning in errors, and unable to address the consequences of these errors without invalidating their own hypothesis. They need to withdraw this claim.
I am more sure now than ever that in particular the ANSYS result was fatally flawed by incorrect dimensions, failure to account for critical elements and assumptions that allowed for the early removal of elements such as the C79 - C44 girder.
An ANSYS model with the correct dimensions and elements accounted for will not fail in the manner that NISTs ANSYS model did.
NIST made a lot of engineering judgement calls here, and these have turned out to have been based on inaccurate input data to their model(s).
Attachments
DGM
Skeptic not Atheist
This is a claim you have not been able to support. Why should we just believe you? Show your work. You do know this is what you need to do before the engineering world will pay attention to you. Do you wish to progress past internet forums?
BTW: Drowning how? You've yet to convince anyone of consequence to pay attention. The NIST is not bothered by you in the least. They weren't even worried when you threatened to tell the Europeans.
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Lots of unproven bare assertions there. That you say so doesn't make it so.
NIST monitored the lateral walk-off distance in ANSYS. Let's for a moment imagine the following scenario: let's imagine that you are right and they got the distance wrong, and after bringing the issue to their attention, they look at the ANSYS output that they monitored and check if the walk-off distance got as big as 6.25". They verify that it was, and issue the correction. What would they need to correct from their report, apart from issuing the errata that they issued?
There was no element to indicate the walk off distance in ANSYS, it was a judgement call on NISTs part.
The required distance of 6.25" does not account for the increased load distribution footprint that the stiffeners would bring to the column.
NIST would need to reconcile the 6.25" walk distance with their previous statement that above 600C the beams would begin to sag and lose their ability to push.
They would also need to account for the expansion of the girder itself and the fact that the girder would become trapped within the inside edge of the column side plate.
NIST will never do this, as it invalidates their supposed initiating event.
ETA they would also have to include the 3 beam stubs that they omitted in their analysis.
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DGM
Skeptic not Atheist
What is that figure?
LSSBB
Devilish Dictionarian
So what difference does a change of reference in the pages below make to the outcome? How many corrections are in the typical government publication of the same size? Does that make them invalid, if the error is unimportant?
Unsupported assertions. Which C79 - C44 girder, by the way, on which floor?
No, they specified an objective criterion: 5.5" (later 6.25") of lateral distance. Objective criterion. Not judgement call. Let me remind you that the quote you brought up citing "engineering judgment" only alluded to the debris falling and causing the collapse of the floors. You still have not proved your assertion that it was a judgement call.
No, it would have made a difference if the girder had shear studs. It didn't, therefore it was basically free to roll off the seat past that distance.
No, they don't. You still need to acknowledge that the seat moved east, enough for the column to break connections in three other floors, and that that reduces the necessary expansion amount considerably.
Not if the girder was pushed first. The temperatures start to raise very close to the border, far away from the girder.
Indeed, but there's abundant proof of fire, and zero proof of explosives. The null hypothesis is therefore that fire brought it down, and no one has ever made even the start of a case showing otherwise.Miragememories said:
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